首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1745篇
  免费   239篇
  国内免费   225篇
耳鼻咽喉   4篇
儿科学   8篇
妇产科学   8篇
基础医学   116篇
口腔科学   44篇
临床医学   103篇
内科学   120篇
皮肤病学   18篇
神经病学   37篇
特种医学   183篇
外国民族医学   1篇
外科学   102篇
综合类   357篇
预防医学   160篇
眼科学   10篇
药学   257篇
  1篇
中国医学   530篇
肿瘤学   150篇
  2024年   1篇
  2023年   20篇
  2022年   37篇
  2021年   72篇
  2020年   61篇
  2019年   51篇
  2018年   51篇
  2017年   83篇
  2016年   103篇
  2015年   77篇
  2014年   141篇
  2013年   186篇
  2012年   174篇
  2011年   177篇
  2010年   129篇
  2009年   115篇
  2008年   114篇
  2007年   106篇
  2006年   87篇
  2005年   83篇
  2004年   54篇
  2003年   47篇
  2002年   52篇
  2001年   33篇
  2000年   24篇
  1999年   11篇
  1998年   9篇
  1997年   15篇
  1996年   14篇
  1995年   9篇
  1994年   9篇
  1993年   9篇
  1992年   9篇
  1991年   7篇
  1990年   5篇
  1989年   8篇
  1988年   3篇
  1987年   8篇
  1986年   2篇
  1985年   8篇
  1984年   3篇
  1983年   1篇
  1979年   1篇
排序方式: 共有2209条查询结果,搜索用时 15 毫秒
1.
目的研究葡萄籽原花青素(GSPs)预处理对脂多糖(LPS)诱导的人牙龈上皮细胞(HGECs)炎症介质表达的影响。  相似文献   
2.
药用淫羊藿开花结实及种子休眠特性研究进展   总被引:1,自引:0,他引:1       下载免费PDF全文
针对药用淫羊藿开花结实与种子休眠特性等问题,从开花结实特性、时空与环境因素等对开花结实的影响、种子休眠特性及解除技术等方面进行了综述。从药用淫羊藿开花结实影响因素调查研究、种子丰产栽培技术研究、快速高效打破种子休眠技术研究、良种选育等方面,提出了提高药用淫羊藿植物结实率与种子发芽率的方法,为相关研究提供参考。  相似文献   
3.
The aim of this systematic review and meta‐analysis was to analyze the effects of grape seed extract (GSE) on glycemic control and serum lipoproteins, inflammation and body weight. Two independent authors systematically searched online databases including EMBASE, Scopus, PubMed, Cochrane Library, and Web of Science from inception until May 30, 2019. Cochrane Collaboration risk of bias tool was applied to assess the methodological quality of included trials. The heterogeneity among the included studies was assessed using Cochrane's Q test and I‐square (I2) statistic. Data were pooled using a random‐effects model and weighted mean difference (WMD) was considered as the overall effect size. Fifty trials were included in this meta‐analysis. Pooling effect sizes from studies demonstrated a significant decrease in fasting plasma glucose (FPG) (WMD): ?2.01; 95% confidence interval (CI): ?3.14, ?0.86), total cholesterol (TC; WMD: ?6.03; 95% CI: ?9.71, ?2.35), low‐density lipoprotein (LDL) cholesterol (WMD: ?4.97; 95% CI: ?8.37, ?1.57), triglycerides (WMD: ?6.55; 95% CI: ?9.28, ?3.83), and C‐reactive protein (CRP) concentrations (WMD: ?0.81; 95% CI: ?1.25, ?0.38) following GSE therapy. Grape seed did not influence HbA1c, HDL cholesterol levels, and anthropometric measurements. This meta‐analysis demonstrated that GSE intake significantly reduced FPG, TC, LDL cholesterol, triglycerides, and CRP levels.  相似文献   
4.
目的:研究甘草种子、种苗质量分级标准,为甘草药材规范化生产奠定基础。方法:以全国主产区所流通的甘草种子、种苗为样本,通过收集种子的发芽率、净度、含水量、千粒质量,种苗的根长、芦头直径和百株质量等指标信息,采用K-均值聚类分析法、标准差法、平均值法并结合生产实践对甘草种子、种苗进行分级,并开展田间栽培比较试验,对等级划分的合理性进行验证。结果:甘草种子质量等级划分为3个等级,各级甘草种子的千粒质量不低于8 g,含水量不低于10%,一级种子:发芽率≥90%,净度≥90%;二级种子:90%>发芽率≥85%,90%>净度≥85%;三级种子:85%>发芽率≥80%,85%>净度≥80%。甘草种苗质量等级划分为3个等级,一级种苗:根长≥45 cm,芦头直径≥0.8 cm,1.3 kg≤百株质量<0.8 kg;二级种苗:45 cm>根长≥35 cm,0.8 cm>芦头直径≥0.6 cm,0.8 kg≤百株质量<0.4 kg;三级种苗:35 cm>根长≥25 cm,0.6 cm>芦头直径≥0.4 cm,0.4 kg≤百株质量≤0.2 kg。结论:经验证,甘草种子、种苗质量等级划分合理,便于生产实践应用。  相似文献   
5.
IntroductionMagseed is an alternative method of localising non-palpable breast lesions that has addressed many of the limitations of wire guided localisation (WGL). It consists of a paramagnetic seed that can be visualised on mammography and ultrasound. Intraoperative localisation of the seed is achieved with the use of the Sentimag probe. The aim of this study was to prospectively compare localisation in patients undergoing wide local excision (WLE) for non-palpable lesions between Magseed and WGL.MethodsWe prospectively collected data on all patients undergoing image-guided WLE between October 2017 and September 2018 in two academic breast units with a planned accrual of 100 consecutive patients undergoing Magseed localisation. Data was also collected on a cohort of 100 consecutive patients undergoing WGL in the same time period.ResultsDemographic and disease characteristics were well balanced between the two groups. 4/104 patients were converted preoperatively from Magseed to WGL (2 misplaced Magseeds; 2 undetected Magseeds). Intraoperative identification and excision of the localised lesion was successful in all patients as confirmed with specimen radiography. Overall no significant differences were observed in the proportion of patients requiring re-excision between the two groups (Magseed 16% vs. WGL 14% p = 0.692). Specimens size by weight and volume was similar for both groups (Magseed 39.6 g vs. WGL 44.5 g p = 0.206 and 90.1 cm3 for Magseed vs. 95.6 cm3 for WGL p = 0.579).ConclusionsIn our series Magseed localisation proved to be as reliable and effective as WGL in terms of lesion identification, excision with tumour free margins and specimen weight.  相似文献   
6.
The present study deals with the evaluation of antiaging potential of carrot seed oil-based cosmetic emulsions. Briefly, cosmetic emulsions composed of carrot seed oil in varying proportions (2, 4, and 6% w/v) were prepared using the hydrophile–lipophile balance (HLB) technique. Coconut oil, nonionic surfactants (Tween 80 and Span 80), and xanthan gum were used as the oil phase, emulgent, and emulsion stabilizer, respectively. The formed emulsions were evaluated for various physical, chemical, and biochemical parameters such as the zeta potential, globule size measurement, antioxidant activity, sun protection factor (SPF), skin irritation, and biochemical studies. The zeta potential values ranged from ?43.2 to ?48.3, indicating good stability. The polydispersity index (PDI) of various emulsion formulations ranged from 0.353 to 0.816. 1,1-Diphenyl-2-picrylhydrazyl- (DPPH) and nitric oxide-free radical scavenging activity showed the antioxidant potential of the prepared carrot seed oil emulsions. The highest SPF value (6.92) was shown by F3 having 6%w/v carrot seed oil. Histopathological data and biochemical analysis (ascorbic acid (ASC) and total protein content) suggest that these cosmetic emulsions have sufficient potential to be used as potential skin rejuvenating preparations.  相似文献   
7.
《Vaccine》2022,40(26):3490-3494
The current WHO Recommendations to assure the quality, safety and efficacy of live attenuated yellow fever vaccines were adopted in 2010. This document recommends that vaccine virus master and working seed lots should be tested for viscerotropism, immunogenicity and neurovirulence in monkeys. A vaccine manufacturer has reported, recently, discrepancies on the clinical scoring of monkeys during assessment of working seed lots and suggested aligning neurotropism assessment of yellow fever vaccines virus seed lots with that of neurovirulence testing of polio vaccines virus seed lots. In this approach, clinical signs are recorded but do not form part of the assessment or pass/fail criteria. At its 71st meeting in August 2020, the ECBS agreed to establish a drafting group and to consult with manufacturers and other stakeholders on the proposed amendment. Then a survey had been conducted to seek opinions of stakeholders on the neurotropism testing and revision of current WHO Recommendations for yellow fever vaccines. It was recognized from the answers of the survey that the test for neurovirulence in monkeys presents several technical challenges which could be addressed in the amended version of the Recommendations.On 18–19 March 2021, a virtual WHO working group meeting was held to discuss a proposed draft of the amended text with participants of yellow fever vaccine manufacturers and relevant regulators. Overall, there was a consensus among manufacturers and regulators that clinical evaluation provides important information and should be retained as part of the neurotropism test. However, there was also agreement that the test is somewhat subjective, and that analysis can be difficult. It was recognized that there was potential for improvement in both test execution and analysis to increase harmonization between manufacturers. Alternative tests to the non-human primates neurovirulence test would be useful but it was agreed that none seem to be sufficiently developed at present. Based on these working group discussions, it was proposed that the appendix on neurotropism test to be further revised by the WHO drafting group and submitted to ECBS for review and adoption.Issues other than neurotropism test were discussed in the meeting as well. There were a number of points identified during the meeting, such as new platform of production, animal models, deep sequencing, international standards, that are outside the current recommendations that are worthy of further discussion. Therefore, it is recommended that there would be a future meeting with various stakeholders to discuss the potential revision of the whole Recommendations for yellow fever vaccines in order to meet the current needs.  相似文献   
8.
This study investigates the effect of the nanostructure of squalene in the form of microemulsion on COVID-19 patients. In this blinded clinical trial, a comparison was made between the efficacy of squalene treatment and controls. A total of 30 COVID-19 patients admitted to the emergency department, and the infection ward was equally allocated to case (n = 15) and control (n = 15) groups according to their age and underlying diseases. The baseline characteristics of subjects, including age, gender, time of treatment onset, underlying condition, white blood cells count, and lymphocyte count were similar (p < 0.05). Baseline laboratory tests and computed tomography (CT) scans were performed for the study groups. The treatment group received 5 mg of intravenous squalene twice a day and standard treatment for 6 days, while controls received only standard treatment. After 6 days of treatment, clinical and CT scan changes were evaluated and compared in intervention and control groups. The need for oxygen therapy (p = 0.020), 2 days of no fever (p = 0.025), cough alleviation (p = 0.010), and lung high-resolution computed tomography improvement (p = 0.033) were significantly different between cases and controls within 7 days of admission. No adverse effects were observed in the treatment group. Our data suggest that squalene could be considered as a potential treatment for COVID-19, and further studies are required to confirm the results.  相似文献   
9.
10.
中药材种子种苗标准对中药材种子种苗生产经营、质量控制及管理至关重要。该文对2020年以前现行各标准包括国际标准、国家标准、行业标准、地方标准、团体标准中涉及中药材种子种苗及地方或民间药用的中药材种子种苗相关的标准进行全面系统整理;从标准发布年度、标准中涉及的中药材基原、中药材种类及其是否被2015年版《中国药典》收载,收载的中药材在2015年版《中国药典》占比等方面进行分析;建议对中药材种子种苗标准的研制应系统化、专业化、可操作,切实保障中药材种子种苗产业健康可持续发展。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号